Selective Laser Melting (SLM, shown in FIG. 1), also known as Direct Metal Laser Sintering (DMLS), Laser Cusing or Selective Laser Sintering (SLS) is an Additive Manufacturing process in which parts are built layer by layer out of a metallic, ceramic or polymer powder.
FIG. 1 illustrates a standard SLM process of the background art. At each step of the process, a powder bed is deposited on a substrate and selectively melted by a laser beam 1 piloted by a CAM system through a scanning head 2. After solidification, the material gets consolidated, a building platform 3 is lowered for the value of the wanted layer height and a new powder layer is deposited by the deposition system 4 containing fresh powder 5. The operation sequence is repeated until completion of the part 6. At the end the unused powder 7 is removed and recycled.
Some of the biggest limitations of parts built by the SLM technology are their inadequate mechanical properties compared to conventionally produced parts. These limitations are well studied and are the result of unfavorable tensile residual stresses (TRS), increased surface roughness, and lower part density. This results in a need for subsequent thermal/mechanical treatment which is limiting the SLM process application.
Another method is disclosed in U.S. Pat. No. 5,316,720. In this patent, a process is disclosed that is used for the compaction and densification of discrete powder materials utilizing a high amplitude stress wave which produces a high pressure condition at a surface of the particles. More specifically, with this process, to manufacture a product, subsequent layers are built up one at a time, first by adding a powder to the surface and then laser shocking the surface and after the particles in each layer have been added, the article made is subjected to sintering to force the added material into tight union with the various surfaces to be bonded.
However, despite these applications in the field of SLM, strongly improved processes are desired to improve device characteristics and manufacturing methods.